I'm getting:
500 - Internal server error.There is a problem with the resource you are looking for, and it cannot be displayed

I suspect the ERP software is running on a remote system and has no idea how to follow your local filepaths (even though you may have a local app that accepts the path. The local app or web browser passes the path C:\1\DDD\123.pdf to the remote server which then can't find DDD.)

How does the ERP software work? Do you use remote desktop to access it? Likely it's running on a system that has access to your local drive when you remote into it but that system doesn't have access to the same servers that you do.

Is there a File-open type dialog box that you can use to browse to your desired location? Does it let you see the servers and shares that you're interested in?

In the Remote Desktop shortcut properties you can configure which local resources your remote system will be allowed to access. perhaps between mapping a drive and configuring these resources you can get this working.

Otherwise, maybe there's someone in the IT department there that can help you configure this.